Process for imparting friction properties to a base material and the resultant product

ABSTRACT

A process for imparting friction properties to a base material such as paper, and the resultant product, wherein the base material has applied to its surface a mixed alumina compositions comprising positively charged colloidal aqueous dispersions whose solids content comprises 25 to 75% of a first alumina component having an ultimate dispersed particle size no more than about one-fifth as great as a second alumina composition comprising 75 - 25% of the solids content.

United States Patent [1 1 Carstens et a1.

1 1 PROCESS FOR IMPARTING FRICTION PROPERTIES TO A BASE MATERIAL AND THERESULTANT PRODUCT [75] Inventors: Ronald A. Carstens, Anacortes; William.I. Butcher, Vancouver,

both of Wash.

[73] Assignee: Key Chemicals, lnc., Anacortes,

Wash.

[22] Filed: Dec. 19, 1973 211 Appl. No; 426,219

Related U.S. Application Data [62] Division of Ser. No. 201,899, Nov,24, 1971, Pat.

[52] U.S. Cl 428/329; 427/372 [51] Int. Cl. B44d 5/08; D21h 1/16 [58]Field of Search 117/127, 130 R, 139.5 CF, 117/169,126 OF, 126GM,152,138.8 R; 252/313 R, 317; 162/181 [56] References Cited UNlTEDSTATES PATENTS 2,734,835 2/1956 Florio et a1. 1. 117/1395 CF July 15,1975 2,786,787 3/1957 Flon'o 117/169 2,909,451 10/1959 Lawler et a1.117/1395 CF 2,931,779 4/1960 White 252/313 R 3,013,903 12/1961 Bugosh117/169 R 3,219,479 11/1965 Le Clercq 117/169 R Primary Examiner-WilliamD. Martin Assistant Examiner-Sadie L. Childs Attorney, Agent, orFirmHolman 8L Stern [57] ABSTRACT 2 Claims, 2 Drawing Figures 1 PROCESSFOR IMPAR'ITNG FRICTION PROPERTIES TO A BASE MATERIAL AND THE RESULTANTPRODUCT This is a divisional of application Ser. No. l,899, filed Nov.24, l97l, now US. Pat. No. 3,8l2,055, issued May 2l, I974.

BACKGROUND OF THE INVENTION l. Field of the Invention:

This invention relates to mixed alumina compositions. More particularly,this invention relates to mixed alumina compositions of differentparticle sizes and to their use in paper manufacturing.

2. Description of the Prior Art:

Methods for economically controlling pitch in paper mill systems havebeen intensely studied for many years. While only a small portion ofavailable pitch actually recirculates in the white water, this is oftenpresent in amounts great enough to agglomerate at various locations,necessitating frequent shutdowns for cleaning purposes. Dispersantsalone are generally ineffective for this purpose, since they merelyfunction to keep the ptich in suspension while its concentration buildsBy maintaining the concentration of pitch in the white water belowcritical levels, the formation of deposits can be substantially reduced.The addition of flocculating agents such as talc, diatomaceous earth andthe like has met with limited success, since the excessive use of suchmaterials tends to weaken and discolor the sheet.

Recently several investigators have reported on the use of colloidalaluminas as paper pitch control agents. While offering significantadvantages over other methods, the cost effectiveness of these materialshas not been sufficient to induce widespread acceptance in the industry.

In addition to their use as pitch control agents, colloidal aluminashave been used as anti-slip agents for frictionizing paper surfaces. Dueto the positive electostatic charge of colloidal aluminas, they arestrongly attracted to negatively charged surfaces such as pitchparticles and paper surfaces. Since the aluminas are water compatible,handling and cleanup problems encountered with silicate colloids areminimized.

In dealing with non-skid paper surfaces, the friction properties of thesurface are commonly measured by determining the slip angle, a measureof the angle at which two contacting non-skid surfaces will begin toslide under controlled conditions. Differences of only a few degrees orso, as determined by accurate testing, may have significant effects onthe ultimate suitability of the papers for various applications.

SUMMARY OF THE INVENTION Accordingly, it is an object of this inventionto provide a composition and method for controlling pitch in papermills.

Another object of this invention is to provide a composition and methodfor imparting anti-slip properties to smooth surfaces.

A further object of this invention is to provide a composition of mixedaluminas having a higher electrostatic charge than either componentalone.

An additional object of this invention is to provide a composition ofmixed aluminas having synergistic properties as compared to theindividual components.

Other additional uses such as for paper mill retention aids andanti-static agents for rugs or similar surfaces will be obvious to thoseskilled in the art.

Briefly, these and other objects, features, and advantages of thepresent invention are provided by mixed alumina compositions comprisingpositively charged colloidal aqueous dispersions whose solids contentcomprises 25 of a first alumina composition having an ultimate dispersedparticle size no more than about one-fifth as great as a second aluminacomposition forming the remainder of the solids content. The dispersionspreferably contain 1 to 15% solids content and have a pH of 0 to 6.These compositions have par ticular utility in controlling paper millpitch, and in providing anti-slip properties to smooth surfaces such ashighly calendered paper surfaces.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 graphically illustrates the slipangles realized by using an anti-slip agent comprising a mixture ofaluminas of generally the same ultimate dispersed particle sizes; and

FIG. 2 illustrates the slip angles realized by using an anti-slip agentcomprising a mixture of aluminas of significantly different ultimatedispersed particles sizes according to this invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS In accordance with the presentinvention, the preferred mixtures comprise about 25 757r ofa firstalumina composition having a particle size of about 4 6 mp, a surfacearea of about 300 m /gm, and a purity of at least about 99% dry weightalpha alumina with a second alumina composition having a particle sizeof about 20 3O mu, a surface area of about I00 m /gm, and a purity of atleast about 97% dry weight alumina. The ultimate dispersion is preparedby adding I to 15%, preferably 3 to 6% and especially about 4%, of thealumina mixture to an acidified aqueous system having a pH of O to 6,preferably 3 to 4.

Conventional additives such as anti-foam agents, cationic or non-ionicsurfactants, corrosion inhibitors, freeze-thaw stabilizers, and the likemay be added in customary proportions. Since the aqueous colloidaldispersion carries a positive charge, the use of anionic surfactants orother additives is generally to be avoided because such additives tendto result in poor or broken emulsions.

The critical feature of the instant invention resides in the mixture ofaluminas having vastly different ultimate dispersed particle sizes, thatis, at least one of the aluminas having an ultimate dispersed particlesize no more than about one-fifth of the other, with about a 25 75%ratio of the first in the mixture. The individual particle sizes,specific surface areas, purities, percent total solids content in thedispersion, and pH of the dispersion as discussed above and hereinafterprovide optimum properties, but as will be seen from the attachedgraphs, it is the use of a mixed particle size that provides unexpectedresults.

In FIG. 1 the solid lines graphically illustrate the straight-lineaverage slip angle in degrees to be anticipated from a mixture of twomaterials having generally the same ultimate particle sizes while thebroken lines illustrate the actual average slip angles in degreesobtained from such mixtures. It will be seen that, in every instance,the mixed compositions provide a result sub stantially below that to beanticipated.

In contrast, by reference to FIG. 2 it will be seen that by mixingaluminas having substantially different ultimate dispersed particlesizes, on the order of 5:1, the resultant anti-slip agent, for the mostpart, provides average slip angles substantially above that to beanticipated. Such a phenomenon is quite unexpected.

Again, while the specific materials described below are not to belimiting on the instant inventive concept, the following properties areset forth as preferred.

Alpha alumina compositions are preferably used as the first aluminacomponent of the present invention and such materials are commerciallyavailable. For example, the material identified as DISPAL M is quitesatisfactory. Preferably the first alumina has an ultimate dispersedparticle size (the particle sizes are always referred to herein in adispersion since upon drying these materials tend to agglomerate) of 2to mp diameter, preferably about 4 to 6 mp.

The second alumina component of the present invention may be of any formbut preferably is of other than the alpha form. Particularly suitableare gamma and delta fumed aluminas. Commercially available materialsidentified as ALON C and Aluminium oxide C are quite suitable, the ALONC providing even better slip angles as seen in FIG. Particle sizes of 10to 100 mp. diameter, preferably of to mu, are preferred.

The two aluminas are admixed in a ratio of 25 to 75% by weight of thefirst alumina with correspondingly 75 to 25% by weight of the secondalumina. Optimal proportions can readily be determined for particularapplication, but will generally contain from to 65% by weight of eachalumina. Particularly good results for many applications are obtainedwith 5O mixtures.

of 2 to 6, preferably 3 to 4, and agitated. Suitable acids includehydrochloric acid, acetic acid, monochloroacetic acid, nitric acid,hydroxyacetic acid, sulfamic acid and the like; halogenated acids arepreferred as they tend to result in more stable dispersions.Concentrated stock dispersions may be diluted with water or acidifiedwater for subsequent use.

The dispersions of the present invention have a positive electrostaticcharge much stronger than that of dispersions prepared with eithercomponent alone. Thus, they are particularly useful in a wide variety ofelectrostatic charge neutralization techniques used to treat negativelycharged materials such as pitch in pulp and paper mills, latex, gums,primary and secondary sewage, and the like. As little as about .03 to .3lb of alumina per ton of stock is generally effective, preferably at apH of about 3 to 6.

The compositions of the present invention are useful in impartinganti-slip friction surfaces to material such as papers, particularlyhighly calendered papers, but including coated and impregnated papers,fiber glass, textiles, some plastics and metals. Dispersions of about0.8 to 8% by weight can be applied to such surfaces by spray, roller, orsponge coating techniques known in the art, although a preferred methodand apparatus for using these materials will be discussed hereinafterwith respect to Example 4 and Table 5.

Having now generally described the invention, it is believed that thoseskilled in the art can utilize it to its fullest extent. The followingExamples are accordingly presented as illustrative and not limiting ofthe remainder of the disclosure.

Table 1 sets forth physical characteristics of the alumina compositionsused in the following Examples, together with characteristics of a fumedsilica composi tion used as a comparison.

with acid added The greater electrostatic charge and resistant to slipresulting from the admixture of small and large alumina particles willnecessarily be somewhat different for different ratios and the optimumeffect will have to be determined for each application. Close packing orloose packing of such minute particles of greatly varying shapes mayresult in varying resistance to slip and electrostatic charge.

The colloidal aqueous dispersions of the present invention are preparedby standard methods, generally to a stock mixture having a high solidscontent of about ID to 40% by weight which may be diluted with water toa solids content of about I to 15% by weight, preferably about 4 to 9%for subsequent use or the alumina powders may be added to acidifiedwater having a pH Slip angles were determined after non-skid applicationby the modified Meyer 16 method. The board to be treated is cut into 4inch wide strips approximately 3 feet long and placed in an oven andpre-heated to about F. to simulate corrugator plant conditions. A 4inches three-fourth inch X three-fourth inch cellulose sponge is soakedin a 10/1 dilution of solution and then when saturated it is squeezedaround in a U shape until the excess liquid runs out. The board is thentaken out of the oven, laid flat on a table and held firmly in place byclamps. The wet sponge is placed on the bottom of the board in front ofan 8/10 mil Meyer Rod along with a piece of wood to push the sponge intothe rod. The board is then coated by running the Meyer Rod and sponge upthe board in one quick motion.

while squeezing the sponge so that the nip between the Meyer Rod andboard is always flooded. The board is then held upside down to drain anyexcess liquid, and

TABLE 3 Continued PROPORTION OF INGREDIENTS AVG. SLIP ANGLE let dry inthe air. In this manner a very dilute solution DEGREES of non-skid isapplied very evenly and uniform slip 5 I FIGURE ZCURVEC angle resultsare obtained by a Key slip angle tester. Alumoma A gg B i 40 O 25 753910 EXAMPLE I 50 50 393 7 8.9 Comparative tests of pitch neutralizationwere perg 3- formed by standard method on representative individ- RE 2CURvE D Alumina A Alumina C ual alumina compositions and mixturesthereof accord- 0 100 35,5 ing to the present invention. ml samples of a0.1% 75 37.2 pitch dispersion taken from a paper mill were treated withvarying volumes of l% alumina solids dispersions lot) 0 37.1 to Hot: thepitch, the resulting mixtures filtered, and the filtrate examinedvisually for clarity. A clear filtrate indicates complete neutralizationof the pitch particles EXAMPLE 3 and resulting floc formation which isfiltered out. Re- Using the following formulation, slip angle tests weresults are presented in Table 2. 20 conducted as described above on boardand paper TABLE 2 FILTRATE APPEARANCE cc of l% Alumina Solids Alumina AAlumina 8" 37.5% A per 20 cc. l% Pitch 62.5% "3 Dispersion like prettycloudy clear clear 5cc pretty cloudy v. slightly clear cloudy 2cc prettycloudy fairly cloudy clear lcc very cloudy fairly cloudy slightly cloudyExpected Neutral Point 10cc lOcc 2cc The above results indicate thatalumina mixtures of coated with various dilutions of the basicformulation the present invention have a much higher electrostatic inactual plant tests. charge than either of the component materials alone,COMPOSITION since only 20% as much of the mixture was required to reachan end point, as compared to the most effective Alumina A 5 WWIndividual component. Alumina B 3 Wm Monochloroacetic Acid .5 wt%Corrosion inhibitor .1 wt% EXAMPLE 2 IPA (for freeze-thaw 3 M54stability) This Example illustrates the mproved slip angles ob Dcfuamcrl W talned on corrugated paper using the compositions of w Balance thepresent invention. All slip angles were measured at sliding pressures of69 gm/sq in. using the Meyer 16 method to apply the composition, andrepresent an av- I Typlcal P angles Obtained the above p erage of atEast Six applications A" dispersions had a tron from actual corrugatmgplant results are shown in total solids content of 3.92 weight Resultsare sum- Table marized in Table 3 and graphically illustrated in theTABLE 4 FIGURES.

It can be seen from the following data that improved Pilution ShippingCartons Bags slip angles are obtained only by mixtures of different Pmedaluminas having the necessary properties such as parti- As is 37 4o35-40 3940 3740 cle sizes and surface areas as described herein. M 37403540:

l13 3540 343 8 TABLE 3 I26 32-37 30-36 l: l() 3034 2832 PROPORTION OFINGREDIENTS AVG. SLIP ANGLE DEGREES 6 A] FIGURE l CURVE A 0 EXAMPLE 4 ggB D 400 Using a l.4 aqueous dilution of the composition of 75 25 38:0Example 3, 50 lb Kraft liner board was coated using the g2 methoddescribed in our copending US. Pat. applica- 0 100 m tion Ser. No. 20|,900 and now U.S. Pat. No. Alumina B QP CURVE 3 3,812,055, filed of evendate with this application and 0 35.5 entitled Method and ApparatusAnti-Slip Applying 25 Anti-sli A ents, the disclosure of which is incoro- 50 so u, i p g 75 25 rated by reference. Briefly, the techniquedescribed I00 0 40.0 therein involves spraying onto an applicator rollerat an 7 8 angle of 90 to 270 from the nip at the top, and passingalumina composition having an ultimate dispersed the board over the topthereof to apply an even film of articl size no more than aboutone-fifth as great anti-slip agent to the board. By spraying onto aroller as a s cond alumina composition; and away from the nip, muchbetter results are obtained b. correspondingly 75-25% by weight of saidsecond than by spraying directly into the nip. Table illus- 5 l mina msition, said second alumina compotrates results obtained by this method.sition having a particle size of about lO-IOO mu.

TABLE 5 Run Spray Angle Top Roller Board Speed Spray Pressure Slip Anglel 270' up 450fpm 30psi 35.5 2 270 down 400fpm 37psi 375 3 270 down540fpm 30psi 375 4 90 down 450fpm 30psi 37.0 5 into nip down 400fpm30psi 33.0"

It will be appreciated that while the foregoing Examand drying thecoated base. ples are directed to preferred embodiments of this in- 2 Pr h vi a Surface coating gompfising a ivention, it is capable ofnumerous alterations or modifitively charged colloidal mixed aluminacomprising: cations as will be apparent to those skilled in the art. a.-75% by weight of the total alumina of a first What is claimed is:alumina composition having an ultimate dispersed l. A process forimparting friction properties to a particle size no more than aboutone-fifth as great base material which comprises applying to the surfaceas a second alumina composition; and of said material a positivelycharged colloidal aqueous b. correspondingly 75-25% by weight of saidsecond dispersion having solid content of l to 15% of mixed 25 aluminacomposition, said second alumina compoalumina comprising: sition havinga particle size of about l0-l00 my a. 25-75% by weight of the totalalumina of a first

1. A PROCESS FOR IMPARTING FRICTION PROPERTIES TO A BASE MATERIAL WHICHCOMPRISES APPLYING TO THE SURFACE OF SAID MATERIAL A POSITIVELY CHARGEDCOLLOIDAL AQUEOUS DISPERSION HAVING SOLID CONTENT OF 1 TO 15% OF MIXEDALUMINA COMPRISING: A. 25-75% BY WEIGHT OF THE TOTAL ALUMINA OF A FIRSTALUMINA COMPOSITION HAVING AN ULTIMATE DISPERSED PARTICLE SIZE NO MORETHAN ABOUT ONE-FIFTH AS GREAT AS A SECOND ALUMINA COMPOSITION: AND B.CORRESPONDINGLY 75-25% BY WEIGHT OF SAID SECOND ALUMINA COMPOSITION,SAID SECOND ALUMINA COMPOSITION HAVING A PARTICLE SIZE OF ABOUT 10-100MU, AND DRYING THE COATED BASE.
 2. Paper having a surface coatingcomprising a positively charged colloidal mixed alumina comprising: a.25-75% by weight of the total alumina of a first alumina compositionhaving an ultimate dispersed particle size no more than about one-fifthas great as a second alumina composition; and b. correspondingly 75-25%by weight of said second alumina composition, said second aluminacomposition having a particle size of about 10-100 m Mu .